Many mobile devices (e.g., smartphones, tablets, etc.) have become the primary photo-capturing devices for many users. These mobile devices often include a flash device to properly illuminate a capture a scene. However, flash devices often consume a significant amount of power on mobile devices. For example, a typical flash may use 1 amp of current across 2-3 frames. Further, the flash intensity is constant while capturing the image, irrespective of the amount of ambient light available at the time. That is, traditional pre-flash metering techniques use a constant flash intensity to expose the image and only control the duration of the flash adjust the scene illumination.
Additionally, traditional pre-flash techniques are slow. For example, in typical flash metering, a pre-flash generally takes 4 to 10 frames for convergence. The length of the pre-flash can depend on various factors such as the scene distance and the amount of ambient light. The slow pre-flash increases the flash snapshot latency.
The embodiments described herein solve these problems, both individually and collectively.